1. Field of the Invention
The present invention relates to an electrostatic processing chamber, which serves as an electrostatic flocking chamber and an electrostatic coating chamber arranged in an electrostatic flocking apparatus and an electrostatic coating apparatus, respectively, wherein: a strip-like elongated workpiece such as steel strips, non-ferrous metal strips and the like is wound into a coil; the coil of the workpiece thus wound is mounted on a delivery unit; in operation, the workpiece of the coil is then unwound and delivered from the delivery unit to assume a strip-like elongated flat plate shape; subsequent to this, the flat plate-shaped workpiece is subjected to an electrostatic flocking operation and an electrostatic coating operation when passed through an electrostatic flocking chamber and an electrostatic coating chamber, respectively, in a condition in which the workpiece is electrically grounded; and, after that, the workpiece is subjected to an after-treatment, and then successively taken up in a take-up unit.
2. Description of the Related Art
When an electrostatic flocking operation and an electrostatic coating operation are performed: an object (to be processed) called xe2x80x9cworkpiecexe2x80x9d is electrically grounded, and oppositely disposed from and spaced a predetermined distance apart from an electrode which is arranged in each of an electrostatic flocking chamber and an electrostatic coating chamber; an high voltage electrostatic energy is applied to the electrode to create an electrostatic field between the workpiece and the electrode, wherein electric lines of force of the electrostatic field thus created extend from the electrode toward the workpiece; at this time, using the electric lines of force, an immense number of short fibers and fine particles of an electrically insulating coating material are floated and electrostatically charged, and therefore electrostatically driven to fly to the workpiece in each of the electrostatic flocking chamber and the electrostatic coating chamber in a manner such that the short fibers and the fine coating material particles are evenly implanted into and applied to the workpiece.
In the electrostatic flocking process and the electrostatic coating process described above, the workpiece is often stationarily supported on a support member which is electrically grounded in each of the electrostatic flocking chamber and the electrostatic coating chamber. At this time, it is also possible to move the workpiece so as to pass through the electrostatic flocking chamber and the electrostatic coating chamber in the electrostatic flocking process and the electrostatic coating process. Further, even when the electrostatic processing operations described above are performed in a condition in which the workpiece is electrically grounded without using the support member, in order to evenly implant and evenly apply the short fibers and the fine particles of coating material into and to the workpiece, it is necessary to perform the above operations for a calculated predetermined operation period of time in a condition in which the workpiece is always spaced a predetermined distance apart from the electrode.
Consequently, in the electrostatic flocking and the electrostatic coating operation of the workpiece traveling through the electrostatic flocking chamber and the electrostatic coating chamber, it is inevitably required to review: the operation period of time required for each of the electrostatic flocking operation and the electrostatic coating operation; and, a traveling speed of the workpiece, at which speed the workpiece travels through each of the electrostatic flocking chamber and the electrostatic coating chamber.
As for types of means for performing both the electrostatic flocking operation of the short fibers and the electrostatic coating operation of the fine particles of coating material, the following types of means are considered: a down-type means, in which the electrode is disposed over the workpiece, while the short fibers and the fine particles of coating material are delivered from above the workpiece to perform the electrostatic flocking operation and the electrostatic coating operation; an up-type means, in which the electrode is disposed under the workpiece, while the short fibers and the fine particles of coating material are delivered from under the workpiece to perform the electrostatic flocking operation and the electrostatic coating operation; and, a side-type means, in which the electrode lies in a plane in which the workpiece lies so that the electrode and the workpiece are arranged side by side in the same plane, whereby the short fibers and the fine particles of coating material are delivered from alongside of the workpiece to perform the electrostatic flocking operation and the electrostatic coating operation.
In case that the electrostatic flocking and the electrostatic coating operation are performed in a condition in which the workpiece assuming a strip-like flat plate shape travels through the electrostatic flocking chamber and the electrostatic coating chamber, and, further, when there is no necessity to reduce the operation period of time, there is also no necessity to consider any improvement of each of the conventional electrostatic flocking chamber and the conventional electrostatic coating chamber in construction.
The reason why this is so because it is sufficient for the workpiece to pass through the electrostatic flocking chamber and the electrostatic coating chamber as is in the conventional processes.
In contrast with this, in order to reduce the operation period of time in the electrostatic flocking and the electrostatic coating operation of the workpiece, and, further, in order to improve these operations in operation efficiency, it is necessary to pass the workpiece through the electrostatic flocking chamber and the electrostatic coating chamber at high speed. Furthermore, in order to thickly at a predetermined thickness and evenly implant and apply the short fibers and the fine particles of coating material into and to the workpiece in the electrostatic flocking and the electrostatic coating operation, respectively, it is necessary to pass the workpiece at high speed through an improved electrostatic flocking chamber and an improved electrostatic coating chamber both of which chambers are improved in construction so as to be capable of thickly at a predetermined thickness and evenly implanting and applying the short fibers and the fine particles of coating material into and to the workpiece, respectively.
Due to the above necessity, it is inevitably required to improve in construction both the electrostatic flocking chamber and the electrostatic coating chamber in a manner such that: a traveling distance of the workpiece between an inlet opening and an outlet opening of each of the electrostatic flocking chamber and the electrostatic coating chamber is increased, that is, an area in which the workpiece is oppositely disposed from the electrode is elongated along the workpiece""s traveling path, which means an increase in longitudinal length of an electrode area in which the electrode is arranged along the workpiece""s traveling path.
In case that the strip-like elongated object or workpiece is light in weight as is in the case of a sheet of paper or cloths: the workpiece is arranged to pass through the electrostatic flocking chamber and the electrostatic coating chamber, in each of which chambers the electrode area described above is increased in its longitudinal length along the workpiece""s traveling path; in performing the electrostatic flocking and the electrostatic coating operation in a condition in which the workpiece travels, there is no fear that the distance between the workpiece and the electrode varies in each of the electrostatic flocking chamber and the electrostatic coating chamber when the workpiece travels through these chambes, since there is substantially no slack in the workpiece when the workpiece is pulled vertically and horizontally so as to travels from the inlet opening to the outlet opening of each of the electrostatic flocking chamber and the electrostatic coating chamber.
Consequently, without specially modifying in construction each of the conventional up-type, the conventional down-type, and the conventional side-type of each of the electrostatic flocking chamber and the electrostatic coating chamber, it is possible to perform the electrostatic flocking and the electrostatic coating operation of the workpiece.
However, in contrast with the case of each of the sheet of paper, cloths and like light-weight workpieces, when the workpiece 1 is any one of steel strips, steel plates and stainless steel strips: since the workpiece 1 is a metal sheet, it is difficult for the workpiece 1 due to its heavy weight to keep its straight shape in both a vertical and a horizontal plane under the influence of gravity when the workpiece 1 travels from the inlet opening 3 to the outlet opening 4 of each of the electrostatic flocking and the electrostatic coating chamber 2. When the workpiece 1 travels in the horizontal plane except the vertical plane, the workpiece 1 suffers from its slack in the electrostatic flocking and the electrostatic coating chamber 2, as shown in FIG. 1. As a result, it is impossible for the workpiece 1 to keep constant the distance between the workpiece 1 and the electrode 5 in a horizontal plane, wherein the electrode 5 is arranged in each of the electrostatic flocking and the electrostatic coating chamber 2.
Any slack produced in the workpiece 1 traveling from the inlet opening 3 to the outlet opening 4 in each of the electrostatic flocking and the electrostatic coating chamber 2 does not satisfy the above-mentioned condition that the distance between the electrode 5 and the workpiece 1 should be kept constant at any time when the electrostatic flocking and the electrostatic coating operation are performed in order to thickly and evenly implant and apply the short fibers and the fine particles of coating material into and to the workpiece 1, respectively. More specifically, when the workpiece 1 slacks to produce a slacked portion and a slack-free portion in the workpiece 1. Due to the presence of such slacked portion and the slack-free portion of the workpiece 1, the distance between the workpiece 1 and the electrode 5 varies in the electrostatic field. This causes variations in line density of the electric lines of force extending from the electrode 5 toward the workpiece 1 in the electrostatic field created between the electrode 5 and the workpiece 1.
The electrostatic flocking and the electrostatic coating operation both performed under the above-mentioned phenomenon fail to evenly drive the short fibers and the fine particles of coating material so as to fly from the electrode 5 toward the workpiece 1, which disadvantageously results in a poorly flocked product and a poorly coated product.
Since in the prior art there is no idea that the workpiece is forced to travel through the electrostatic flocking and the electrostatic coating chamber at high speed, any consideration is not made in this respect in the prior art.
Since the electrostatic flocking process and the electrostatic coating process are based on the same principle, such principle will be first described.
Each of the technology of the electrostatic flocking process and the technology of the electrostatic coating process is based on an essential idea that: the electrode, to which the high voltage electrostatic energy is applied, is provided; the electrostatic processing chamber havs a construction in which the electrode is oppositely disposed from the workpiece which is electrically grounded, wherein the high voltage electrostatic energy is applied to the electrode so that the workpiece is electrically charged; the electrostatic field is produced between the electrode and the workpiece to make it possible to use its electric lines of force in electrically charging the fine things which float between the electrode and the workpiece in the electrostatic processing chamber forming a housing; and, the fine things thus electrically charged are driven to fly toward the workpiece being electrostatically processed.
The technology of the electrostatic flocking process considerably differs from the technology of the electrostatic coating process in the following points: the technology of the electrostatic flocking process uses the short fibers as the fine things, wherein the short fibers are electrostatically charged; the workpiece to be electrostatically processed is electrically grounded , and has its surface coated with an adhesive layer which remains undry; and, the short fibers are electrostatically driven to fly toward the adhesive layer of the workpiece, and have their front end portions implanted into the adhesive layer of the workpiece under the effect of electric lines of force appearing in the electrostatic field created between the electrode and the workpiece, whereby the workpiece is flocked with the short fibers.
On the other hand, in the technology of the electrostatic coating process: the fine things floating in the housing for performing the electrostatic processes are the fine particles of a powder coating material or of a liquid coating material; the workpiece is electrically grounded, and not coated with any adhesive layer; the fine things of the liquid coating material or of the powder coating material are electrostatically charged; the electrostatic field is created between the electrode and the workpiece to produce the electric lines of force; and, by using these electric lines of force, the fine things of the liquid or powder coating material are electrostatically driven to fly toward a surface of the workpiece, whereby the liquid or power coating material is adhered to the surface of the workpiece under the effect of the electrostatic energy.
Both the above processes are based on the same principle that: the electrostatic field is created between the workpiece and the electrode; and, the electric lines of force appearing in the electrostatic field are used in the processes. However, these processes differ from each other in the conditions of the workpiece and in material of the fine things which are electrostatically charged and floated.
In other words, the above processes are identical with each other in that the housing which forms the electrostatic processing chamber has a construction in which: the electrode is arranged so as to be oppositely disposed from the workpiece electrically grounded; and, the electrostatic field is created between the electrode and the workpiece, which produces the electric lines of force extending from the electrode toward the workpiece.
In view of the above circumstances, the present invention was made. Consequently, it is an object of the present invention to realize an even flocking and an even coating operation of a workpiece, under the condition that: a work piece, for example such as elongated ferrous metal plates, non-ferrous metal plates and the like, is wound into a coil and has its surface coated with an adhesive layer; the workpiece of the coil is unwound to assume a strip-like elongated shape; when the elongated workpiece is subjected to an electrostatic flocking and an electrostatic coating process, any slack of the workpiece due to its own weight under the influence of gravity is forcibly prevented from occurring when the workpiece travels through each of an up-type electrostatic flocking and coating chamber from its inlet opening to its outlet opening, wherein an electrode area in which an electrode is arranged is increased in its longitudinal direction along the workpiece""s traveling path; when the workpiece travels through the electrostatic flocking and the electrostatic coating chamber, the workpiece is always spaced a predetermined distance apart from the electrode arranged in each of the electrostatic flocking and the electrostatic coating chamber, so that it is possible to prevent the electric lines of force extending from the electrode toward the workpiece from varying in intensity at the surface of the workpiece, wherein the slack of the workpiece causes the electrostatic field created between the workpiece and the electrode to vary in intensity at the surface of the workpiece, which causes in turn the electric lines of force extending from the electrode to the workpiece to vary in intensity at the surface of the workpiece described above, whereby the short fibers and the fine particles of coating material are electrostatically driven to fly from the electrode toward the workpiece in a predetermined condition; and, under such predetermined condition, it is possible to realize an even thickness flocking and an even thickness coating operation of the workpiece.
The above object of the present invention is accomplished by providing:
A structure of an electrostatic processing chamber of an electrostatic flocking apparatus, wherein: a strip-like elongated workpiece is constructed of a metal strip of a material selected from the group consisting of ferrous metal and non-ferrous metal, wherein the metal strip has its surface coated with an adhesive layer to form the strip-like elongated workpiece which is wound into a coil, wherein the coil of the workpiece is mounted on a delivery unit; the strip-like elongated workpiece is passed through an electrostatic flocking chamber at high speed so that the workpiece is electrostatically flocked with short fibers; after completion of such electrostatical flocking of the workpiece with the short fibers, the workpiece is subjected to an after-treatment, and then taken up in a take-up unit, characterized in that: a pressure roller for defining a Valley-shaped (V-shaped) oblique surface portion of the workpiece is arranged between an inlet opening and an outlet opening of the electrostatic flocking chamber, wherein the workpiece""s V-shaped oblique surface portion substantially corresponds in position to a curved surface portion of the workpiece formed under the influence of gravity due to the workpiece""s own weight when the workpiece travels through the electrostatic flocking chamber; and, an electrode is disposed parallel to the V-shaped oblique surface portion of the workpiece.
Further, the above object of the present invention is accomplished by providing:
A structure of an electrostatic processing chamber of an electrostatic coating apparatus, wherein: a strip-like elongated workpiece is constructed of a metal strip of a material selected from the group consisting of ferrous metal and non-ferrous metal, wherein the metal strip is wound into a coil, wherein the coil of the workpiece is mounted on a delivery unit; the strip-like elongated workpiece is passed through an electrostatic coating chamber at high speed so that the workpiece is electrostatically coated with an electrically insulating coating material; after completion of such electrostatical coating of the workpiece with the coating material, the workpiece is subjected to an after-treatment, and then taken up in a take-up unit, characterized in that: a pressure roller for defining a V-shaped oblique surface portion of the workpiece is arranged between an inlet opening and an outlet opening of the electrostatic coating chamber, wherein the V-shaped oblique surface portion of the workpiece substantially corresponds in position to a curved surface portion of the workpiece formed under the influence of gravity due to the workpiece""s own weight when the workpiece travels through the electrostatic coating chamber; and, an electrode is disposed parallel to the V-shaped oblique surface portion of the workpiece.
In the structure of the present invention having the above construction: since the workpiece is always spaced a predetermined distance apart from the electrode when traveling a relatively long distance through the electrostatic processing chamber such as the electrostatic flocking chamber and the electrostatic coating chamber, it is possible for the floating short fibers having been electrostatically charged to have their front end portions evenly implant into the adhesive layer of the workpiece, and, further, it is possible to evenly apply the floating fine particles of coating material having been electrostatically charged to the surface of the workpiece.
In other words, it is possible for the present invention to obtain the workpiece having been evenly flocked with the short fibers and the workpiece having been evenly coated with the coating material.